Grain⁃based model and analysis of deep hard rock considering intragranular structure characteristics of mineral

Macroscopic properties of rock materials are controlled by their meso⁃structures. With the continuous devel⁃ opment of rock multi⁃scale mechanics research， the grain⁃based model ( GBM ) with grain breakable characteristics has gradually become a powerful tool in this field. The corresponding relationship between the intragran⁃ ular mesh morphology and the crystal structure of rock minerals has received less attention in previous studies. Re⁃ search on the influence of the intragranular mesh morphology on the calculation results of the grain⁃based model is rel⁃ atively limited，which is not conducive to the further refinement of the model and the comparative analysis of calcula⁃ tion results of different models. Based on the existing research，using the Neper plug⁃in combined with Universal Distinct Element Code，six intragranular meshing modes are established comprehensively considering the cleavage charac⁃ teristics of mineral crystals. The influence of different intragranular mesh methods on the calculation results is analyzed based on the uniaxial compression simulation test. Results show that the proposed intragranular mesh method can re⁃ produce the cleavage characteristics of mineral grains，therefore provide a variety of options for the refined construction of discrete element models. The difference of intragranular mesh mode has the most obvious influence on uniaxial com⁃ pression strength but has little influence on Poisson′s ratio and elastic modulus. The stability of mechanical parameters is jointly affected by the shape of the sub⁃grains and the uniformity of the intragranular path direction，The shape of the sub⁃grains has a more significant effect. The amount of microcracks are mainly related to the geometric characteristics of the sub⁃grains. Compared with the triangular sub⁃grains，the polygonal sub⁃grains are more likely to cause an in⁃ crease in the overall number of micro⁃cracks. The increase in the roundness of sub⁃grains will weaken the interlocking effect between the grains，resulting in a decrease in the number of cracks. Therefore，the influence of the model con⁃ struction method on the calculation results should be fully considered when using the GBM so as to improve the relia⁃ bility of simulation.